Liquid crystals of silver complexes derived from simple 1-alkylimidazoles

A homologous series of silver complexes of 1-alkylimidazoles (R-im, R = CnH2n+1, where n = 10, 12, 14, 16 and 18) was synthesized. All the CnH2n+1-im ligands are non-mesomorphic. Upon complexation, all the [Ag(CnH2n+1-im)(2)]-[NO3], except for n = 10, exhibit liquid crystalline properties. The crystal structure of [Ag(C12H25-im)(2)][NO3] shows that the silver center is two-coordinate and adopts a U-shaped conformation with bilayer packing. The non-mesomorphic [Ag(C16H33-bim)(2)][NO3] (bim = benzimidazole) has a three-coordinate silver ion and has a chair conformation with monolayer stacking. Non-mesomorphic [Ag(C16H33-bim)(2)][BF4] has a linear geometry around the silver ion and also has a chair conformation. The mesophase for the Ag-(CnH2n+1-im) complexes has been identified as the smectic A (SmA) phase. [Ag(C16H33-im)(2)](+) with four different anions, NO3-, BF4-, PF6- and CF3SO3- were compared. Of the four Ag-im complexes, only tht with the CF3SO3- anion does not show liquid-crystal behavior.